1. Field of the Invention
The present invention relates to a spline-coupling structure comprising a male member having a set of spline teeth provided on an outer periphery thereof and a female member having another set of spline teeth provided on an inner periphery thereof. At least one of the sets of spline teeth have crownings thereon. The sets of spline teeth are coupled with each other by press-fitting the members, with each other, along an axial direction thereof.
2. Description of the Related Art
Such structure is already known from Japanese Utility Model Application laid-open No. 97655/87 and Japanese Utility Model Application laid-open No. 5515/92.
In the prior art structures, crownings are provided on at least one of the two sets of spline teeth on the members, thereby facilitating the mutual press-fitting of the members and providing a sufficient coupling force upon the completion of the press-fitting. However, an end face of each of the members is connected with tooth flanks, bottom lands and tooth crests of the spline teeth to form acute angle portions by one another. For this reason, when the members are press-fitted, one into another, the following disadvantages are encountered, due to a damaging attendant on a dragging produced at the angle portions, irrespective of the crownings being provided: The press-fitting load is increased; actually press-fit coupled areas of the spline teeth are reduced, whereby a sufficient coupling force fails to be provided; and a lubricating oil passage is clogged with residues produced due to the dragging. In addition, although the crownings are intended to facilitate the disengagement of both the members from each other and, hence, enable reuse of, both members if there is no damage thereto, however, it is difficult, not only to conduct the disengagement of the members from each other, but also to reuse such members when the dragging damages the members.